Well-known are machines of end-face rotor-stator interaction type, where the rotor is a disk, on the end surfaces whereof permanent magnets of alternating polarity are located over the circumference. The stator of such machines is made in the shape of a disk (ring), installed coaxially with the rotor, electromagnetic stator coils being located at the end faces of the stator. For instance, the direct current brushless electric motor (electric drive) described in U.S. Pat. No. 5,440,185, IPC 6 H02K 21/12 belongs to this type of electric machines. The known device includes at least one rotor installed on the shaft and made as a multi-pole magnetic disk consisting of sections spaced along the circumference, where the polarity of the sections alternates. The device also includes at least one disk-shaped stator element, determining the rotor position, the device for mounting the rotor (rotors) and stator element (elements) on the common axle, the sensor for positioning the multi-pole magnetic disk versus the stator element and a device to identify the magnetic field profile in the stator elements. Two windings are wound over the stator elements, electric current being fed to one of those thus determining the polarity of the stator poles. The known device is not easy in manufacturing, the biggest difficulty being manufacturing of disk-shaped rotors with magnetic poles of alternating polarity.
The closest analogue to the invention being claimed is an electric machine with a rotor having claw-shaped poles (V. A. Balagurov, F. F. Galateyev. Electric Generators with Permanent Magnets.—Moscow: “Energiya”, 1988, pp. 31-32). The rotor in a machine of this type is a polygon or cylindrical, axially magnetized permanent magnet; to the end surfaces whereof two disks with horns jutting out like “claws” on the poles are fixed. The disks are made of magnetically soft material, all poles of one disk being northern, and of the other one—southern. The pole horns are oriented in parallel to the generatrix of the permanent magnet cylinder while the rotor disks are shifted against each other in such a way that the poles of the one are between the poles of the other.
In order to increase the power of the machine, the rotor is made of multiple sections. At that several sections are mounted on the same shaft, each consisting of two disks with claw-shaped poles and a polygon or cylindrical magnet magnetized in the axial direction located between them. When the multi-sectional rotor is being assembled, the magnets in the adjacent sections are oriented towards each other respect to their like poles.
The known designs of electric machines with claw-shaped rotors have an advantage of being equipped with only one magnet tightly fixed between two disks. This ensures high impact strength of the rotor. At the same time such rotors are rather difficult to manufacture. Besides, at high revolutions under the influence of centrifugal forces the “claws” may bend out. To prevent this the device should be reinforced, which results in its heavier weight. Since it is radial interaction between the rotor and the stator that is actualized in the known design, the machines of this type are of great radial dimensions.